life.clj

(defn next-gen [b r c]
  (let [neighbors (fn [[cell :as [i j]]]
                    (remove #(= % [i j])
                            (for [x (filter (-> r range set) (range (- i 1) (+ 2 i)))
                                  y (filter (-> c range set) (range (- j 1) (+ 2 j)))]
                              [x y])))
        alive? (fn [[cell :as [i j]]]
                 (nth (nth b i) j))]
    (for [i (range r)]
      (for [j (range c)]
        (let [live-nb (count (filter true? (map alive? (neighbors [i j]))))]
          (or (= 3 live-nb) (and (alive? [i j]) (= 2 live-nb))))))))

(defn life [r c]
  (loop [x 100
         b (partition r (take (* c r) (repeatedly #(zero? (rand-int 5)))))]
    (let [nb (next-gen b r c)
          delim (str \+ (apply str (repeat (count (first b)) \-)) \+)
          render (apply str (for [r nb] (str "|" (apply str (map #(if % \# \space) r)) "|\n")))]
      (println (str (apply str (repeat 50 "\n")) delim "\n" render delim))
      (Thread/sleep 100)
      (if (and (pos? x) (not= nb b))
        (recur (dec x) nb)
        (println "\nStopped after" (- 100 x) "iterations" (if (zero? x) "(limit)" ""))))))

(life 20 20)